4.To the silver nitrate solution, add concentrated
ammonium hydroxide drop by drop until the precipitate formed is JUST
clear. Excess ammonia may cause a precipitate or result in a poor
impregnation of the fibers. If ammonia is added too much, add few
more drops of 10% silver nitrate solutions to make solution JUST
becomes cloudy.

5.Place slides back in this ammonium silver solution and
stain in 40 ºC oven for 30 minutes or until sections become dark
brown (may not look very dark brown if the sections are only 10 um
thick and may look very dark brown if the sections are 30 um thick).

6.Place slides DIRECTLY (do not wash slides) in
developer working solution for about 1 minute or less (reaction may
be very fast, so test a slide, check microscopically to determine
exact incubation time).